Degradation Of Ship Grey Water By Ozonation Combined Biofilm And Cyclone

As a major part of ship’s domestic sewage,ship grey water is characterized by high COD,BOD value,surfactant and oil content,etc.There is still a lack of efficient and specialized degradation technologies and devices.In this study,the combination of cyclone,ozone oxidation and biofilm method is proposed and used to degrade ship grey water and to explore the efficient and economy for the purification of ship grey water.The main research contents include:ozone oxidation combined with biofilm to degrade ship grey water and its process optimization,process optimization of cyclonic flow combined with ozone oxidation to treat ship grey water,and cyclonic flow and ozone oxidation combined with biofilm method to degrade ship grey water.Details are as follows:1.The degradation effect of ozone oxidation combined with biofilm on ship grey water was investigated in detail.First,the experimental setup was built,the effects of different ozone infusion time,initial p H and reaction temperature on oil,COD and ammonia nitrogen of ship grey water treated by ozone oxidation were investigated,and the suitable process parameters were found out by single-factor experiments as ozone infusion time of 9 min,initial p H of 9.5 and reaction temperature of 30℃.Under this condition,the COD removal rate was 68.09%,oil removal rate was 70.93%and ammonia nitrogen removal rate was35.93%.The effects of hydraulic retention time（HRT）,initial p H and reaction temperature on the removal of oil,COD and ammonia nitrogen on effluent in moving bed biofilm reactor were investigated,which was transferred to it after ozone-oxidization.The results showed that the removal rates of COD,oil and ammonia nitrogen reached 86.33%,81.04%and 70.49%,respectively,at 9 h HRT,initial p H 9 and temperature of 23℃.Then,the ozone oxidation treatment of ship grey water was optimized using the response surface methodology,and the optimum ozone influx time of 10.5 min,initial p H of 8.5,and reaction temperature of 30℃were obtained,and the experimental COD removal rate was 77.9%,oil removal rate was 75%,and ammonia nitrogen removal rate was 38.8%.2.The effect of the cyclone combined with ozone for degradation grey water was also studied.A single-factor experiment was conducted after the installation of the cyclone combined ozone method,and the oil removal rate was 81.82%and the COD removal rate was61.79%when the ozone gas flow rate was 0.1 L·min^-1 and the grey water inlet flow rate was1.2 L·min^-1.An orthogonal experiment was designed and ANOVA was performed to determine the best kind of gas.The experiment showed that oil removal rate of 81.82%when ozone gas flow rate 0.1 L·min^-1 and gray water inlet flow rate 1.2 L·min^-1.3.The effect of combined biofilm,cyclone and ozone process for degrading ship grey water was finally studied.On the basis of the above two chapters of equipment,the effect of different initial p H and circulation time on the effect of cyclone and ozone oxidation on the degradation of oil,COD and ammonia nitrogen in ship grey water was studied.The effect of moving bed biofilm reactor on the removal effect of pollutants under different hydraulic retention time was obtained by changing the hydraulic retention time,and p H before and after the reaction.The removal rate of oil was 74.1%,COD was 78.4%and ammonia nitrogen was79.5%when the initial p H was 8,the circulation time was 5 min and the hydraulic retention time was 5 h.The three processes combination were compared.The results showed the combination of cyclonic flow,ozone oxidation and biofilm method is better than two other processes combination.In current study,a combination of cyclone,ozone oxidation and biofilm process was proposed and used to degrade ship grey water.An experimental rig was built and experiments were carried out to study the process parameters.It is effective in achieving the discharge requirements for oil,COD and ammonia nitrogen concentrations in ship grey water.